Can NI RS-485/2 PCI card support 8 data bits with 2 stop bits

[griffin]

Hi,

I have a NI 485/2 card, and we are having trouble setting/keeping it with 8 data bits and 2 stop bits. If we run a short program (also with labview), using portmon we see an error message when setting the stop bits. If I use the advanced setting in the windows hardware port window, set it for 8 data bits and 2 stop bits and exit, when I go back in it has reset to 1 stop bit without having my having done anything else. However, if I set it for 7 data bits and 2 stop bits it seems to keep the values, and I can also then set it to 8 data bits and it appears to keep the two stop bits. However, when I then run the program, portmon again shows an error on setting the stop bits and when I look using the windows menu it has been reset to 1.

The program call nevertheless reports a success, and inquiring the state gives back 2 stop bits.

Any help would be appreciated.

Thanks

Frans

[craigherdman]

Frans,

I would recommend making the COM port settings in MAX. You can see all of your ports under Devices and Interfaces and you can click on a port number to set the Port Settings. Any changes made here (that we Save) are reflected in the Windows Device Manager. You should be successful in setting your ports to 8 data bits with 2 stop bits after that. I'm not really sure why the changes wouldn't have been made in Windows however. What version of Windows are you running?

Craig H.
NI Applications Engineering

[griffin]

Craig,

Thanks for your suggestion. We are busy looking at the traffic on the cable so that we can be sure of what is being transmitted and received. If we learn anything of general interest I will post a summary, or any further questions.

We are running this on Windows XP.

Frans